Lubricant



Patented Nov. 8, 1949 LUBRICANT Theodore G. Roehner, Mount-Vernon, andGeorge W. Murray, Pleasantville, .N. Y., assignors to Socony-Vacuum OilCompany, Incorporated, a corporation of New York No Drawing. ApplicationApril 1'7, 1948, Serial No. 21,756

: Claims. (01. 252-421) V This invention relates to lubricants and, moreparticularly, is concerned with lubricants characterized by a high orderof effectiveness under severe operating conditions.

It is well known that lubricants generally lose some or all of theireffectiveness when subjected to high temperature and pressureconditions, and this is particularly true of greases exposed to suchconditions. In lubricating machine parts with a grease, it is essentialto provide a grease which will substantially retain its character un--der the foregoing conditions. Failure to do so results in highconsumption of the lubricant and frequent servicing. In general,available greases suffer from a marked tendency to change-in characterwhen used over a wide range of temperature. For example, the consistencyof a conventional grease is prone to change over a Wide range oftemperature. Certain soda base greases, for

example, have a pronounced and undesirable property of changing from ashort to a long fibre structure with temperature change. Someconventional greases are also characterized by excessive softening whenexposed to elevated temperatures, thereby being extruded too rapidlyfrom the area being lubricated to provide efficient lubrication. "Inaddition, some greases tend to lose their oil content when used atelevated temperatures and pressures. This condition is generallyreferred to in the art as bleeding.

In accordance with the present invention, there has now been discoveredaggrease which is char .acterized by a high order of effectiveness widersevere operating conditions and which is substantially free from theshortcomings discussed above. "The greases contemplated herein contain,as a characterizing or reinforcing agent. a small amount of a-water-dispersible or oil-insoluble and water-soluble proteinaceousmaterial, representative of which are the water-dispersible proteins andhigh molecular weight amino acids derived therefrom by hydrolysis.Typical of the proteinaceous materials contemplated as reinforcingagents in the greases of this invention .are casein, gelatin, arginine,aspargine, and the albumins, .such as egg albumen and the like. Whileuse of one :or more of the above substances represents a preferredembodiment of the invention, it .is likewise contemplated that otherwater-dispersible pnoteinaceous material-s known in the .art

2 may be employed in improving the heat resistant characteristics of thegreases described herein.

The greases of this invention containing one or more of the aforesaidcharacterizing agents are the alkali metal and alkaline earth metal basegreases; that is, those grease compositions consisting of mineral oil inadmixture with alkali metal or alkaline earth metal soaps of fatty acids.or with a sufficient proportion of such soaps'preslent to give thecharacteristics usually recognized as attributable to alkali andalkaline earth metal base greases. The soap content of these greases isgenerally between about '10 and about per cent by weight on the basis ofthe final product. They are generally prepared by heating a fat .or afatty acid, or a mixture thereof, with a mineral :oil and thereafterheating the resultant mixture with the desired metal hydroxide atelevated temperatures $0 obtain a substantially anhydrous metal basegrease. The final product so obtained generally contains 8.5 to 48 percent "fat or fatty .acid; 1.5 to 7.5 per cent metal hydroxide (drybasis) and 29.5 to 89.5 per cent mineral oil. In obtaining the grease,the mixture may be cooked, {for example, at temperatures of 250 to 400F. Available steam-cooked greases do not maintain their shape atelevated temperatures and firecooked greases are typified by bleedingunder such conditions;

The mineral oil constituent of the greases contemplated herein may varyconsiderably in character and includes residual or distilled oils.Preference is accorded, however, to oils having a viscosity of '(S. U.V.) of to 250 seconds at 210 F. Similarly, the fats and fatty acidswhich may be used are those generally found in the soap type greases.Representative of such materials are vegetable, animal, and fish fattyoils, and hydrogenated fatty materials thereof. While sodium ydroxidecalcium hydroxide are preferred in viewof cost considerations and agreater demand by industry for :soda and lime base greases, other metalhydroxides may be used in the present greases, preferably where'thesoapeconstituent of the grease is prepared by directsa-ponification inaqueous phase. Accordingly, such other metal hydroxides as those oflithium, potassium, magnesiumj, barium, strontium, etc, are contemplatedherein, with the alkali :metal hydroxides pretened.

It has been found, in accordance with this invention, that from one totwo parts by weight of alkali or alkaline earth metal soap may bereplaced with one part of water-dispersible protein to yield a resultinglubricating grease composition characterized by resistance todeformation and bleeding. The particular degree of substitution of soapby the water-dispersible protein will depend in part on the nature ofthe soap being replaced. Thus, in the case of a sodium base grease,approximately one part by weight of water-dispersible protein willreplace one and onehalf parts by weight of soap, while with a calciumbase grease, approximately one part by weight of protein may besubstituted for two parts by weight of soap. Likewise, the extent ofsubstitution of soap by water-dispersible protein depends on the natureof the soap being replaced. It is generally contemplated, however, thatthe replacement of soap by protein will not exceed about 30 per cent ofthe soap content. Thus, in the case of a soda base grease, it has beenfound that up to 30 per cent of the soap could be replaced withwater-dispersible protein. For example, 50 per cent soap in a soda basegrease may be replaced with 35 per cent soap and per cent ofwater-dispersible protein. In the case of a lime base grease, up to percent of the soap may be replaced with water-dispersible protein. Forinstance, 50 per cent soap content in a lime base grease may be replacedwith 40 per cent of the same soap and 10 per cent of water-dispersibleprotein.

It will thus be apparent that the characterizing materials of thisinvention may be used in various amounts extending over a range of fromabout /2 per cent to about 15 per cent. Preferred amounts for the alkalimetal greases, such as soda base grease, are of the order of /2 per cent'to 6 per cent and for the alkaline earth metal greases, typified bylime base grease, are from about /2 per cent to about 3 per cent byweight of the finished grease.

It has further been discovered that the characterizing water-dispersibleproteins described above are most advantageously incorporated in thesoap greases prior to or during the saponification stage, as illustratedby the following procedure. A fatty or fatty acid, or mixture thereof,is added to mineral oil in order to provide a blend thereof; ifnecessary, the materials may be heated in order to thoroughly distributethe fatty material in the mineral oil. The characterizing material ofwater-soluble or water-dispersible protein is then dissolved ordispersed in water and the resulting water solution is dispersed oremulsified with the blend of fatty material and mineral oil. Theresulting dispersion or emulsion is thereafter saponified with a metalhydroxide solution such as caustic soda. Following the latter treatment,water-of solution and of reaction-is evaporated by heatin and stirringthe saponified mixture at a temperature above about 220 F., preferablyat 260 F. In this evaporation operation, the saponified mixture may alsobe steam-cooked at temperatures of the order of 250 to 330 F. orfire-cooked at temperatures in the range of 300 to 450 F. The grease isthen withdrawn from the vessel in which it was prepared and run into asuitable mold. The grease is allowed to cool, whereupon it solidifies.The solid grease may then be cut into cakes of desired size. Byfollowing this preferred procedure, the characterizing water-dispersibleprotein is incorporated in the grease in an extremely fine dispersedstate and the grease is provided with a high order of effectiveness.

The greases of this invention are illustrated by the following typicalexample:

Example An amount of one part by weight of gelatin (U. S. P. powder) wasdispersed with stirring in 50 parts of cold water. Forty-four parts ofmineral oil (S. U. V. of seconds at 210 F.) and 30 parts of a fattymaterial were then added with stirring to the gelatin solution andheated. The fatty material was a mixture of hydrogenated fatty acids (24parts) obtained by hydrogenation of fish oil fatty acids andhydrogenated fat (6 parts) obtained by hydrogenated fish oil fat. Thegelatin-oil-fat solution was heated at about F. and agitated vigorously,whereupon an emulsion was obtained. Caustic soda solution (45 per centaqueous solution-4V parts) was added to the emulsion at 160 agitationbeing completed in 10 minutes. The mixture thus obtained was heated andagitated for 3 hours at 280 F. to complete the saponification and wassubstantially dehydrated (water content 0.1 per cent) thereafter byheating or fire-cookin to a temperature of 330 F. The grease was thenallowed to cool, whereupon it solidified. The final product, hereinafterreferred to as Grease I, is identified by the following characteristics,all figures being on a dry basis:

Grease I Percent Hydrogenated Fatty Acids 30.3 Hydrogenated Fat 7. 3Sodium Hydroxide. 5. 7 Mineral Oil 55. 45 Gelatin 1.25

Grease II Percent Hydrogenated Fatty Acids 30. 65 Hydrogenated Fat. 7.4Sodium Hydroxide 5. 8 Mineral 0il 56.15 Gel None Grease II was preparedby direct saponification of fatty materials and mineral oil with astrong caustic solution in the proportions indicated above andthereafter was substantially dehydrated.

One-inch cubes were cut from 1" thick grease slabs which wererepresentative cross sections, of the grease blocks under test. Thecubes were placed on an open tray and the tray was placed on a shelf ina constant temperature electric oven. The cubes were heated at 250 F.for one hour, at 300 F. for one hour, and finally at 350 F. withoutbeing removed from the oven. After each of the aforesaid heatingperiods, the top side of each cube was slightly pressed down with theflat side of a spatula to determine whether there was any deformation orslumping of the cube. In order to pass the test, the sample should showonly a slight spreading at the base of the cube and no free oil at thebase of the cube after the third test period of 350 F. The results(average of 4 tests) of these tests are tabulated below:

from about 8.5 to about 48 per cent of a fatty material, about 1.5 toabout 7.5 per cent of so- Dimensions of Test Cubes 2321323: Per CentGrease in 1, Decre a.se Oil at Base Before Heating After Heating AreaHelght Base 1.00 x 1. 00 1.125" x l. 125 I {Height H 1. 00;; I, 0. sex27 13 N919- x {88 25 62? 64 38 Considerable.

It will be apparent from the foregoing results that Grease I, whichcontains gelatin, is greatly superior to Grease II in its resistance tobleeding, as shown by the oil extruded from the latter grease and alsoin its substantially smaller degree of deformation. The improved greasesof this invention are excellent lubricants for locomotive drivingjournals where high temperatures and pressures are encountered. Theyalso find application as anti-friction bearing greases; for example,ball bearing and roller bearing greases. Other applications for theseimproved greases will be apparent to those skilled in the art.

The characterizing materials of this invention, as pointed out above,may be used in various amounts in imparting improved properties togreases. In general, the various constituents (on a dry basis) ofgreases contemplated herein may vary within the following limits:

Per cent Fatty material 8 -48 Alkali 1 /z--.'? Mineral oil 29 /289 /2Protein It is to be understood that the greases of this invention mayalso contain other characterizing agents and fillers. For example, theymay contain grease anti-oxidants, such as amines, phenols, sulfides,etc.; fillers, such as asbestos, graphite, mica, talc, etc.; andlubricity improving agents, such as free fat, free fatty acids,sulfurized fats, and lead soaps.

It is to be understood, moreover, that the foregoing specific examplesare but representative of the greases contemplated herein. The presentinvention, therefore, is not to be construed as limited thereto but isto be broadly interpreted in the light of the claims appended hereto.

This application is a continuation-in-part of co-pending applicationSerial Number 602,667, filed June 30, 1945, now U. S. Patent 2,441,720.

We claim:

1. A lubricating grease composition prepared from about 8.5 to about 48per cent of a fatty material, about 1.5 to about 7.5 per cent of analkaline material selected from the group consisting of alkali metalhydroxides and alkaline earth metal hydroxides, about 0.5 to about 15per cent of a water-dispersible protein, and the balance, mineral oil.

2. A lubricating grease composition prepared from about 8.5 to about 48per cent of a fatty material, about 1.5 to about 7.5 per cent of analkaline material selected from the group consisting of alkali metalhydroxides and alkaline earth metal hydroxides, about 0.5 to about 15per cent of gelatin, and the balance, mineral oil.

3. A lubricating grease composition prepared from about 8.5 to about 48per cent of a fatty material, about 1.5 to about 7.5 per cent of analkali metal hydroxide, about 0.5 to about 6 per cent of awater-dispersible protein, and the balance, mineral oil.

4. A lubricating grease composition prepared dium hydroxide, about 0.5to about 6 per cent of gelatin, and the balance, mineral oil.

5. A soda soap lubricatin grease characterized by resistance todeformation and bleeding, comprising sufficient mineral oil to form saidgrease, a sodium soap content of from about 10 to about 55 per cent andfrom about 0.5 to about 15 per cent of a water-dispersible protein.

6. A soda soap lubricating grease characterized by resistance todeformation and bleeding, comprising sufiicient mineral oil to form saidgrease, a sodium soap content of from about 10 to about 55 per cent andfrom about 0.5 to about 6 per cent of gelatin.

7. A lubricant selected from the group consisting of alkali metal basegreases and alkaline earth metal base greases characterized byresistance to deformation and bleeding, comprising sufficient mineraloil to form a grease, a soap content of from about 10 to about 55 percent and from about 0.5 to about 15 per cent of a water-dispersibleprotein.

8. A lubricant selected from the group consisting of alkali metal basegreases and alkaline earth metal base greases characterized byresistance to deformation and bleeding, comprising sufiicient mineraloil to form a grease, a soap content of from about 10 to about 55 percent and from about 0.5 to about 15 per cent of gelatin.

9. A lubricating grease composition characterized by resistance todeformation and bleeding, comprising the reaction products of thefollowing ingredients in the indicated proportions:

Per cent Fatty material 8 -48 Alkali 4- 1 /2 Mineral oil 29 /z89 /gWater-dispersible protein -15 10. A lubricating grease compositioncharacterized by resistance to deformation and bleeding, comprising thereaction products of the following ingredients in the indicated propor-The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 149,996 Cook et al. Apr. 21, 18741,410,967 Thompson Mar. 28, 1922 2,108,644 Brunstrum Feb. 15, 19382,303,558 Kaufman et al. Dec. 1, 1942 2,346,124 Dew Apr. 4, 1944

